Usage of permeate water for treated domestic wastewater by direct capillary nanofiltration membrane in agriculture reuse

摘要

Direct Capillary Nanofiltration (Direct CNF) is a new technique used for surface water and wastewater treatment in one step without pre-treatment. The CNF membrane module combines the favourable cleaning properties of capillary ultrafiltration membranes with the favourable separation properties of nanofiltration membranes in terms of removal of DOC, colour, bacteria, viruses and pesticides. In this study, Direct CNF has been applied to waste-water treatment under continuous and stable process conditions. The optimum conditions for Direct CNF when applied to domestic wastewater were 15min filtration time, 20L/m~2h flux rate with undiluted domestic wastewater under stable conditions for 19 h and 20min continuously. Direct CNF showed high removal for bacteria, heavy metals, COD, BOD_5, DOC and medium removal for manganese, calcium and magnesium while lower removal was detected for mono valent ions such as sodium and chloride. The permeate of CNF was high quality water that can be used for agriculture purposes but presence of a few counts of bacteria and high ammonia and total nitrogen concentrations shows that the permeate water needs further treatment. Accordingly, the permeate water was treated with granular activated carbon followed by low chlorine doses for disinfection to produce water that can be used for agriculture purposes of any type of crop.